Elastic membrane



FIG. 1 is a top perspective view of an elastic membrane showing our new design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a front view thereof, a rear view being identical thereto;

FIG. 6 is a right-side view thereof, a left-side view being identical thereto;

FIG. 7 is a cross sectional view taken along section line 7-7 in FIG. 3 ; and,

FIG. 8 is an enlarged portion view take along line 8-8 of FIG. 7 .

The broken lines in the drawings depict portions of the elastic membrane that form no part of the claimed design. 

CLAIM The ornamental design for an elastic membrane, as shown and described. 